System for hydrocarbon extraction in oil/gas wells

ABSTRACT

An arrangement for extracting hydrocarbons in oil wells, of the type having a wellhead and an extraction assembly comprised of a fluid collecting container, a suction tube extending inside the fluid collecting container and an extraction rod provided with a plunger that moves inside the extraction tube and which allow to carry out the extraction of hydrocarbons without the need of having equipment or suction pumps/pressurization.

FIELD OF THE INVENTION

The present invention relates to a system or arrangement employed in oilfield wells for extracting hydrocarbons, and more particularly it relates to a system for extracting liquid and gaseous hydrocarbons, which requires no suction pumps or pressurization for the rise of oil collected from the depths of the well.

BACKGROUND OF THE INVENTION

In the oil industry, more particularly in exploration, the so-called low pressure or semi-exhausted wells are known, which are wells that over time and their exploitation contain a quantity of oil and gas pressure that impose the use of special equipment and techniques to extract these products still remaining in the well.

One of the solutions to the problem of extracting the remaining gas and oil that is employed is disclosed in U.S. Pat. No. 7,866,381 belonging to the same owner of the present invention. Said patent relates to an arrangement for the extraction of hydrocarbons comprising an extraction assembly consisting of a container, hose or fluid collecting tube and a suction tube, and which is housed inside a casing pipe, typically the well casing pipe. The suction tube extends along the hose or collecting tube, which has an open upper end, through which end passes the upper section of the suction tube at whose end is fixed to a pulling wire of the aforementioned assembly. In its turn, the hose or collecting tube has a lower end closed by a one-way check valve which allows the entry of fluid into the space between the hose or collecting tube and said suction tube. The upper section projecting beyond the upper end of the collecting tube has laterally formed a fluid discharge hole. The operation of the device is based on the fact that the “hose-collecting tube/suction tube” assembly is lowered into the mass of oil and once the oil has filled the collecting tube or hose, the assembly rises by the action of the pulling wire up reaching the end of its path. There said discharge hole is positioned in a watertight chamber of the wellhead defined between a pair of sealing rings, so as to allow discharge of fluid through the suction of a pump connected to the chamber or, when internal pressure in the well is available, using the gas pressure that exists inside the casing pipe.

U.S. Pat. No. 6,854,518 is also known which discloses a method that reduces the pressure of the upper section of a well, aiding in the production of gas and oil. The device is comprised of a production tube housed within a casing pipe. The method is to reduce the pressure of the upper section of the wellbore by means of a pump so as to reduce the pressure in the surface fluid. It produces pressure reduction at the bottom of said production tubing, causing an increase in the pressure difference between the ground and the interior of the casing pipe. At the same time, pressure is reduced through the production tube which reduces the density of the column of fluid therein. This effect further reduces the pressure in the production tube until it can reach equilibrium. It is clear that in the case of oil production wells where depths reach thousands of meters, suctioning fluid by means of a tube from the surface requires excessive power to generate the pressure differences that are necessary.

Patent U.S. Pat. No. 6,464,012 discloses an oil extraction system having one cylindrical container suitable for being inserted into the casing pipe. The container is coupled to a cable to lower it into the oil which enters at the bottom of the container having a sphere which stands on a hole of said container, so as to allow the entrance but not the exit of oil. The cylindrical container at the top has a hole where a pressure air supply line is placed when the container moves upwards and is positioned against an air injection nozzle. The fluid in the container travels through a suction pipe by means of holes therein on its bottom. From the air supply line, air pressure is simultaneously supplied which enters the container pushing oil through the suction pipe thereby emptying the container and supplying oil through a discharge port that the device has at one of its sides. The pressurized air supply is achieved by a container tank of the pressurized fluid which generates maintenance costs of high pressure values without considering the risk of explosion implied by injecting air into a container with hydrocarbon.

Moreover, there are different systems for extracting fluid from wells, water systems for example, employing a pipe for rising extraction fluid and a stem with a lower plunger provided with one-way check valve for loading water or other fluid within the pipe and pushing it upwards by an alternative vertical movement of the stem. By using these systems, however, great powers for driving very expensive motor machinery are required, which investment is justified for very high production wells.

As it has been seen, part of systems known operate with suction pumps or pressurization of the well or with long chains of suction rods that have not shown the expected efficiency for the extraction of hydrocarbons, especially in wells of low production, this is why it would be very desirable to have a new arrangement that does not require expensive suction pumps or pressurization and that may operate mechanically by a suction rod with plunger confined within a submersible oil collecting pipe, operating said suction rod only in a delimited section or length just near the surface.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a hydrocarbon extracting arrangement or system that avoids the use of suction pumps or pressurization to perform the extraction of fluid from the collecting tube.

It is still another object of the present invention to provide an extracting system having a new extracting assembly comprised of a rod and a plunger that are in operative communication with a plurality of discharge openings through which the discharge of fluid into a flowline is carried out.

It is further another object of the present invention to provide an extracting system which reduces related operating costs and also allows the optimization of the physical space of the place.

It is still another object of the present invention to provide a system for extraction of hydrocarbons in oil wells, the system comprising:

a wellhead connected to a well casing pipe and having at least one outlet chamber defined between a top seal and a lower seal, and

an extraction assembly connected to a pulling wire to move up and down inside the casing pipe, said extraction assembly comprising:

a fluid collecting container capable of collecting oil when submerged into oil of the well and having an open upper end for entry of oil therein when submerged, and a closed lower end,

an extraction tube extending into the collecting container and affixed thereto, the extraction tube having an upper end provided with at least one opening capable of connecting fluidly with said outlet chamber of the wellhead for discharging oil collected in the collecting tube and in the extracting tube, said at least one opening of the extraction tube being outside the collecting container, and the extraction tube has a lower end having an extraction check valve,

an extraction rod connected to said pulling wire and arranged within said extraction tube for moving up and down inside the extraction tube,

a lower plunger at a lower end of said extraction rod, said plunger being in sliding and sealing contact against an inner wall of said extraction tube, and

a plunger check valve in said plunger, with the plunger check valve and the extraction check valve operating to open in the same one-way sense, whereby any oil collected in the collecting container passes into the extraction tube, through the plunger and extraction check valves, when the oil enters the submerged collecting container.

BRIEF DESCRIPTION OF THE DRAWINGS

For better clarity and understanding of the object of the present invention, several figures are provided, in which the invention has been illustrated and embodied in one of the preferred embodiments, all by way of example, wherein:

FIG. 1 shows a schematic and sectional view of the system for extracting hydrocarbons of the present invention together with a surface actuator and wellhead;

FIG. 2 shows a sectional view de the extraction system according to the present invention;

FIG. 3 shows a sectional and enlarged view of a section of the extraction system of the invention, more particularly of the section corresponding to the wellhead and an oil outlet chamber;

FIG. 4 shows a sectional view of the lower portion of the extraction system of FIG. 3;

FIGS. 5 and 6 show a sectional view of the extraction system of the invention when it is in the fluid filling or loading position; and

FIGS. 7 and 8 show a sectional view of the extraction system of the invention when it is in the discharge position.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to figures, it is seen that the invention consists of a new extracting system for extracting hydrocarbons which system is incorporated on the surface of an oil well. As it is known, a casing pipe is installed along the depth of said well, which casing is cemented around the well walls for obtaining a rigid and fixed support position relative to the ground. Said casing tube reaches such a depth that it contacts hydrocarbons to be extracted. Generally, said hydrocarbons are present in liquid state with solid particles and in gaseous state at a given pressure. As explained in relation to the prior art, often there are cases where oil wells do not have the internal pressure required for the fluid to flow easily to the surface without the aid of pumping elements. These wells, which may be somewhat depleted or semi-emptied require pumping devices and systems to extract-lifting the remaining oil. However, the use of pumping systems incurs high costs because of the expensive suction pumps or pressurization. For these reasons, the present invention aims to remove hydrocarbon without using suction pumps or pressurization, thus reducing costs and allowing optimization of physical space of the place.

According to FIGS. 1 to 8, the extraction arrangement or system of the present invention is indicated by the general reference 1 and has a wellhead 2 arranged above a well surface, a reel or surface actuator 3 mounted near said wellhead 2, and wound thereon, there is provided a pulling wire 4 which is connected to the upper end of an extraction assembly 5 by which the extraction of oil shall be carried out. It is emphasized that, said assembly 5 is moved vertically inside the well, reaching such a depth so as to contact oil and be submerged in it.

Wellhead 2 has an upper extension tube 6 having an upper end which is provided with an upper cover 7 on which a compression sealing plug 8 is mounted provided with a cone seal 9 through his said pulling wire 4 guidely passes. Furthermore, said upper extension tube 6 has two upper 10 and lower 11 end run limit sensors, which detect the position of the extraction assembly 5 at their desired end positions. An outlet chamber 12 is defined within extension tube 6, between an upper seal 13 and a lower seal 14, arranged at a lower end of the extension tube 6. Said oil outlet chamber 12 is defined between tube 6 and an extraction tube 20 and the chamber is connected to at least an oil pipeline through a discharge port 15, see FIG. 7. In turn, said wellhead 2 has at least a safety valve 16 arranged below said outlet chamber 12 and connected to a flange 17 as best illustrated in FIG. 3.

Moreover, and referring again to the extraction assembly 5, it is comprised of a fluid collecting container 18 having an open upper end 19, with openings for oil entry therein, and a closed lower end. Also, there is provided the above mentioned extraction tube 20 that is fixed to said fluid collecting container 18 and has an upper end provided with at least one discharge opening 21 for discharging the lifted oil, with the at least one opening 21 being always arranged above the upper end of the fluid collecting container 18 and outside container 18. Extraction tube 20 has a lower end that is arranged near or close to the lower end of the fluid collecting container 18. In addition, extraction assembly 5 is connected to said pulling wire 4 allowing raising and lowering thereof, as mentioned above. It is emphasized that, said extraction tube 20 and the container 18 are joined together by any means, whether by radial seams, welding, etc. that allows that collection container 18, with its upper end open 19, and extraction tube 20 move integrally, together, up and down during the operation of extraction assembly 5 and under the action of wire 4.

Extraction tube 20 has at its upper end, a sealing plug 22 together with respective O-rings 23, which seals against upper seal 13 of oil outlet chamber 12. At the opposite end of tube 20, namely the lower end, an inlet foot tube 24 is provided, the tube having an upper end provided with a valve seat 25 in which there is operatively housed a one-way extraction check valve 26 which allows the passage of oil from collecting container 18, via tube 24, into extraction tube 20. The distance between the lower end of tube 20 and the lower end of container 18 will be the one desired in order to remove as much as possible any oil remaining at the lower end of container 18. Said one-way extraction check valve 26 comprises a ball 27 which is housed within a ball holder 28. In order to keep extraction tube 20 closed into collecting tube 18, collecting tube or container 18 has a top plug 29 and bottom plug 30. Extraction tube 20 sealingly passes through plug 29.

According to the object of the present invention, extraction system 1 has an extraction rod 31 mounted in a longitudinally movable way inside said extraction tube 20 and passes through sealing plug 8 that seals around and against extraction rod 31. In a lower end of extraction rod 31 a lower plunger 32 with a one-way check valve 33 is provided. Valve 33 faces one-way extraction check valve 26 and both valves 33, 26 open in the same sense to permit the oil collected into collection tube 28 to pass upwardly through valves 26 and 33 into tube 20, above plunger 32. Plunger 32 is in sliding and sealing contact against the interior wall of said extraction tube 20.

Extraction rod 31 has an upper end threaded to a connecting head 34, arranged above and separated at a distance from the sealing plug 22, and a lower end threaded to said plunger 32 and secured by a nut 35. In turn, said plunger 32 comprises a valve guide 36 within which said one-way check valve 33 moves, and valve 33 comprises a valve holder 37 which operably receives a small ball or ball 38 also forming a seat for said ball 38. In addition, and in accordance with the invention, extraction assembly 5 is provided with a compression spring 39 within which passes said extraction rod 31, with said spring 39 having an upper end fixed to said plug 22 of the extraction tube 20, and a lower free end 40 able to abut against a hub of said rod or against plunger 32 in its upward movement.

Regarding the operation of the extraction system of the present invention, when it is desired to fill the extraction assembly 5, FIGS. 5 and 6, reel 3 lowers the extraction assembly 5 inside the well up to the depth corresponding to the level of oil inside the casing tube, permitting assembly 5 to submerge into the oil. When submerged, the oil enters into the collecting container 18 through the openings 19 in the upper end of tube 18. Once inside the collecting container 18, the fluid enters also the extraction tube 20 passing upwardly through one-way check valves 26 and 33.

Once filled, FIGS. 7 and 8, the extraction assembly 5 is lifted and the weight of the fluid stored in the extraction tube 20 pushes the one-way check valve 33 downwards, closing the fluid passage and retaining the oil into tube 20, above valve 33. Collection tube 18 and extraction tube 20 are lifted together, as a unit, by the operation of the reel 3 which pulls from pulling wire 4 connected to head 34 of extraction assembly 5. Assembly 5 is raised to a given height at which top plug 29 of container 18 is adjacent to a base platform 41 of wellhead 2. Also, sealing plug 22 of extraction tube 20 seals against top seal 13 of extension pipe 6, and discharge openings 21 of extraction 20 are positioned within outlet chamber 12. In order to carry out the discharge of fluid contained in tube 20 through discharge openings 21, and discharge port 15, the reel 3 continues to raise head 34, which is connected to extraction rod 31, thereby allowing plunger 32 to push the fluid column upwards as it goes up until sensor 10 is driven by connecting head 34. During the lifting of the oil contained in extraction tube 20, above plunger 32, such oil still remaining in the annular volume between extraction tube 20 and collection tube 18, is suctioned to pass through ball valve 27 in order to enter the volume into tube 20 below plunger 32. Therefore, when all the oil within extraction 20, above plunger 32, has been discharged, extraction rod is lowered within tube 20, also assisted by spring 39, and the oil in tube 20, below plunger 32, is compressed, therefore raising through ball valve 38 and entering extraction tube 20. Rod 31 is raised again and the oil is discharged, as explained before, through openings 21, chamber 12 and discharge port 15. These operations are repeated until all the oil collected into collection tube 18 is discharge. In this way, the pumping effect carried out by rod 31 and plunger 32 is achieved by moving the plunger only along a minimum distance once the large amount of oil has been raised by collection tube 18. During extraction operations this movements between the sensor 10 and 11 are performed several times until all of the fluid inside the tube is discharged. Once the oil contained inside collection tube 18 is discharged, the operation of lowering the extraction assembly 5 is repeated, thus submerging tubes 18, 20 into the oil, filling the tubes with collected oil and raising the system again to discharge to the oil to a desired container at the surface.

Thus, the extraction system of the present invention is constituted and built, wherein the use of suction pumps or pressurization is avoided to carry out the extraction of hydrocarbons, due to the arrangement of the extraction rod 31 in conjunction with the plunger 32 which are moved vertically inside the extraction tube. 

1. A system for extraction of hydrocarbons in oil wells, the system comprising: a wellhead connected to a well casing pipe and having at least one outlet chamber defined between a top seal and a lower seal, and an extraction assembly connected to a pulling wire to move up and down inside the casing pipe, said extraction assembly comprising: a fluid collecting container capable of collecting oil when submerged into oil of the well and having an open upper end for entry of oil therein when submerged, and a closed lower end, an extraction tube extending into the collecting container and affixed thereto, the extraction tube having an upper end provided with at least one opening capable of connecting fluidly with said outlet chamber of the wellhead for discharging oil collected in the collecting tube and in the extracting tube, said at least one opening of the extraction tube being outside the collecting container, and the extraction tube has a lower end having an extraction check valve, an extraction rod connected to said pulling wire and arranged within said extraction tube for moving up and down inside the extraction tube, a lower plunger at a lower end of said extraction rod, said plunger being in sliding and sealing contact against an inner wall of said extraction tube, and a plunger check valve in said plunger, with the plunger check valve and the extraction check valve operating to open in the same one-way sense, whereby any oil collected in the collecting container passes into the extraction tube, through the plunger and extraction check valves, when the oil enters the submerged collecting container.
 2. The system of claim 1, wherein said wellhead has an upper extension tube into and along which said extraction rod moves up and down, the extraction rod having an upper end connected to said pull wire.
 3. The system of claim 2, wherein said upper extension tube has an upper end run limit sensor and a lower end run limit sensor.
 4. The system of claim 1, wherein the extraction rod passes through a sealing plug in said extension tube, the sealing plug seals around and against the extraction rod
 31. 5. The system of claim 1, further comprising a compression spring with extraction rod passing along and inside the compression spring, said spring having an upper end fixed to a sealing plug in the upper end of the extraction tube and a lower free end capable of abutting against the plunger in an upward movement of the plunger.
 6. The system of claim 2, wherein said outlet chamber is connected to at least an oil pipeline via a discharge port in the extension tube.
 7. The system of claim 1, wherein said extraction assembly is connected to said pulling wire through a connecting head.
 8. The system of claim 1, wherein said extraction rod has an upper end threaded to said connecting head and said lower end of the extraction rod is threaded to said plunger.
 9. The system of claim 1, wherein the extraction check valve of the extraction tube comprises a one-way extraction check valve that comprises a ball which is housed within a ball holder and a seat for the ball.
 10. The system of claim 1, wherein the plunger check valve is a one-way check valve 33 comprising a valve boll and a seat in a valve holder
 37. 